#  Copyright 2026 zhaoxi826
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

from kilostar.core.postgres_database.model.user import User
from sqlalchemy import select
from kilostar.utils.error import UserNotExistError, UserPasswordError
from kilostar.core.postgres_database.database_exception import database_exception
from kilostar.core.postgres_database.model.user import UserAuthority
from kilostar.utils.access import Accessor


class AuthDatabase:
    """User 表的 DAO：注册、登录、改密、删除以及权限读写。"""

    def __init__(self, async_session_maker):
        self.async_session_maker = async_session_maker

    @database_exception
    async def add_user(self, user_name: str, hashed_password: str) -> User:
        """新建一名用户；若当前库中尚无任何用户，第一名将被自动赋予 SUPER_ADMINISTRATOR 权限。"""
        from ulid import ULID

        async with self.async_session_maker() as session:
            # Check if any users exist
            statement = select(User).limit(1)
            results = await session.execute(statement)
            existing_user = results.first()

            authority = UserAuthority.USER
            if existing_user is None:
                authority = UserAuthority.SUPER_ADMINISTRATOR

            user = User(
                user_id=str(ULID()),
                user_name=user_name,
                hashed_password=hashed_password,
                user_authority=authority,
            )
            session.add(user)
            await session.commit()
            await session.refresh(user)
            return user

    @database_exception
    async def change_password(self, user_name, old_password, new_password) -> User:
        """校验旧密码后将其替换为新密码；旧密码不匹配抛 UserPasswordError。"""
        async with self.async_session_maker() as session:
            statement = select(User).where(User.user_name == user_name)
            results = await session.execute(statement)
            user = results.scalar_one_or_none()
            if user is None:
                raise UserNotExistError()
            if not Accessor.verify_password(old_password, user.hashed_password):
                raise UserPasswordError()
            user.hashed_password = Accessor.hash_password(new_password)
            session.add(user)
            await session.commit()
            await session.refresh(user)
            return user

    @database_exception
    async def delete_user(self, user_name: str) -> None:
        """按用户名删除一名用户，不存在则抛 UserNotExistError。"""
        async with self.async_session_maker() as session:
            statement = select(User).where(User.user_name == user_name)
            results = await session.execute(statement)
            user = results.scalar_one_or_none()
            if user is None:
                raise UserNotExistError()
            session.delete(user)
            await session.commit()

    @database_exception
    async def delete_user_by_id(self, user_id: str) -> None:
        """按用户 ID 删除一名用户，不存在则抛 UserNotExistError。"""
        async with self.async_session_maker() as session:
            user = await session.get(User, user_id)
            if user is None:
                raise UserNotExistError()
            session.delete(user)
            await session.commit()

    @database_exception
    async def login_user(self, user_name: str) -> str:
        """按用户名查出 User 记录返回给上层；上层再做密码校验并签发 token。"""
        async with self.async_session_maker() as session:
            statement = select(User).where(User.user_name == user_name)
            results = await session.execute(statement)
            user = results.scalar_one_or_none()
            if user is None:
                raise UserNotExistError()
            return user

    @database_exception
    async def get_all_users(self) -> list[User]:
        """返回数据库中全部用户列表。"""
        async with self.async_session_maker() as session:
            statement = select(User)
            results = await session.execute(statement)
            users = results.scalars().all()
            return list(users)

    @database_exception
    async def get_user_authority(self, user_id: str) -> UserAuthority:
        """返回指定用户的 UserAuthority 枚举；不存在抛 UserNotExistError。"""
        async with self.async_session_maker() as session:
            user = await session.get(User, user_id)
            if user is None:
                raise UserNotExistError()
            return user.user_authority

    @database_exception
    async def change_user_authority(
        self, user_id: str, new_authority: UserAuthority
    ) -> User:
        """
        Changes the authority level of a specific user.

        Args:
            user_id: The ID of the user whose authority is to be changed.
            new_authority: The new authority level to assign to the user.

        Returns:
            User: The updated user object.

        Raises:
            UserNotExistError: If the specified user does not exist.
        """
        async with self.async_session_maker() as session:
            user = await session.get(User, user_id)
            if user is None:
                raise UserNotExistError()
            user.user_authority = new_authority
            session.add(user)
            await session.commit()
            await session.refresh(user)
            return user